class Person:
    def _init_(self,name):
        self.name = name
        self._age = 1
def set_age(self,new_age):
    if 0 < new_age <= 120:
        self._age = new_age
def get_age(self):
    return self._age
person = Person("小明")
person.set_age(20)
print(f"年龄为{person.get_age()}岁")